A Novel Mechanism of Macrophage Activation by the Natural Yolkin Polypeptide Complex from Egg Yolk

Abstract

Ageing is accompanied by the inevitable changes in the function of the immune system. It provides increased susceptibility to chronic infections that have a negative impact on the quality of life of older people. Therefore, rejuvenating the aged immunity has become an important research and therapeutic goal. Yolkin, a polypeptide complex isolated from hen egg yolks, possesses immunoregulatory and neuroprotective activity. Considering that macrophages play a key role in pathogen recognition and antigen presentation, we evaluated the impact of yolkin on the phenotype and function of mouse bone marrow-derived macrophages of the BMDM cell line. We determined yolkin bioavailability and the surface co-expression of CD80/CD86 using flow cytometry and IL-6, IL-10, TGF-β and iNOS mRNA expression via real-time PCR. Additionally, the impact of yolkin on the regulation of cytokine expression by MAPK and PI3K/Akt kinases was determined. The stimulation of cells with yolkin induced significant changes in cell morphology and an increase in CD80/CD86 expression. Using pharmaceutical inhibitors of ERK, JNK and PI3K/Akt, we have shown that yolkin is able to activate these kinases to control cytokine mRNA expression. Our results suggest that yolkin is a good regulator of macrophage activity, priming mainly the M1 phenotype. Therefore, it is believed that yolkin possesses significant therapeutic potential and represents a promising possibility for the development of novel immunomodulatory medicine.

Importance for humans of recently discovered protein compounds – yolkin and yolk glycopeptide 40, present in the plasma of hen egg yolk

“…This complex at 100 µg/mL possessed the same or even higher cytokine-inducing activity than the lipopolysaccharide (LPS) used as a positive control. Subsequent studies have shown that purified Y polypeptide complex possesses immunomodulatory activity, which was confirmed in the human whole blood (as ex vivo model), mouse bone marrow-derived macrophages of the BMDM cell line, and murine macrophage-like cell line J774.2 (as in vitro models) ( Polanowski et al, 2012 , 2013 ; Zambrowicz et al, 2017 ; Kazana et al, 2020 , 2022a ).…”

“…The impact of Y on the secretory activity of the human whole blood ex vivo has been studied most extensively because the use of unseparated whole blood cultures mimicked the natural microenvironment in which the different leukocyte populations (such as TH1 and TH2) and macrophages can cooperate. Y complex purified from IgY was found to efficiently induce pro-inflammatory factors such as interferons α/β ( IFNs α/β ), interleukin 1 beta ( IL-1β ), interleukin 6 ( IL-6 ), chemotactic interleukin 8 (IL-8) and tumor necrosis factor-alpha ( TNF-α ) controlling the cellular immune response, and anti-inflammatory cytokine interleukin 10 (IL-10) ( Polanowski et al, 2012 , 2013 ; Zabłocka et al, 2014 , 2021a ; Kazana et al, 2020 , 2022a ).…”

“…The modulatory effect of polypeptide complex Y on the immune system is also due to its ability to activate nitric oxide (NO) production ( Zabłocka et al, 2014 ; Kazana et al, 2020 , 2022a ). NO is a molecule that exerts beneficial results in the body as an antibacterial, antiparasitic, antitumor, and antiviral agent ( Tripathi et al, 2007 ).…”

“…To explain the molecular mechanism of Y immune activity, Kazana et al (2020 , 2022a ) examined its impact on the maturation and function of macrophages in bone marrow-derived macrophages of the BMDM cell line in a mouse model.…”

“…In addition to being a versatile food product, eggs are a rich source of high-quality nutritive substances, many of which exhibit multifunctional properties such as foaming, gelling, emulsifying, and coloring ( Anton, 2013 ; Li et al, 2021 ). Hen eggs, in particular, are an excellent source of raw materials for the development of health-promoting functional foods, that is, nutraceuticals, and natural pharmaceuticals, garnering significant attention in recent years ( Mine, 2007 ; Réhault-Godbert and Guyot, 2018 ; Réhault-Godbert et al, 2019 ; Kazana et al, 2020 , 2022a , b ). Although the bioactive compounds in the egg white and yolk have been well-characterized, limited information is available on the proteins present in the egg yolk plasma other than immunoglobulin Y ( IgY ).…”